The recent identification of transcription factors (TFs) that can induce conversion of fibroblasts into pluripotent stem (IPS) cells makes it potentially possible to generate patient-specific neurons from fibroblasts. However, the neurons thus produced are difficult to obtain. The present project builds on preliminary results demonstrafing that it is possible to direcfiy convert adult fibroblasts or other adult non- neuronal cells into neurons, referred to as 'induced neuronal cells' (iN cells), without an iPS intermediate. The resulfing IN cells have all ofthe functional properties of neurons, including the ability to form funcfional synapses as assayed electrophysiology. Thus, the IN cell technology provides a novel, more facile approach to generating and studying human neurons, and opens up a new avenue to invesfigafing neurons from patients with various neurodegenerafive diseases. However, at this point the IN cell technology has only been employed to fibroblasts from young mice, and the effect of aging on iN cell generation and/or the generation of IN cells from human fibroblasts have not yet been established. Therefore, the present application proposes experiments in three specific aims that will systematically investigate the effect of aging on iN cell generafion (specific aim 1), develop the technology to generate IN cells from human fibroblasts (specific aim 2), and use the IN cell technology to study the properties of mouse and human neurons containing mutafions that are known to cause Alzheimer's disease (specific aim 3). These aims will be pursued by a combinafion of fissue culture experiments with cells cultured from mice and humans, cell biology, molecular biology, and electrophysiology. Together, the experiments proposed in this applicafion will develop a new avenue for studying human neurons and for invesfigafing the relationship of aging and neurodegenerafion, with the long term goal of using this technology for a better understanding of human aging and human disease. RELEVANCE (See instructions): This application will develop methods to generate neurons direcfiy from non-neuronal cells, allowing the production of neurons from skin fibroblasts of human patients. These methods will then be used to test the effects of aging and of Alzheimer's disease mutations on neuronal biology, with the long-term goal of establishing a better understanding of how aging and Alzheimer's disease alter neuronal function.